My husband is about to start Sutent -- would it be beneficial to be on vitamins or a supplement.
Good luck to Don as he starts out on Sutent.
The first thing to say is do run the idea past his oncologist first to ensure he doesn't take anything that's known to potentially create problems. Unless he goes overboard on them, he's unlikely to suffer any harm from taking vitamin supplements and may very well derive useful benefits.
The theory is that we get all the vitamins and other micronutrients we need from a well-balanced diet. However, the typical modern American diet is appalling (and here in the UK is not perfect either, where we tend to follow on behind US trends). So, there is a real case to be made for taking vitamins to make good on possible dietary benefits and this is much more important as we get older. For instance, most older people get out into sunshine less than when younger and suffer the adverse consequences of a resultant vitamin D deficit.
However, you need to know what it makes sense to choose and doctors are generally uneducated on nutrition which, along with mental health issues, is a sadly overlooked component of medical education. For instance, most vitamin D preparations come with added calcium and that can be the last thing some people need (cancer patients have their calcium levels checked regularly via blood tests so that can be established for Don).
There are some excellent books on diet and lifestyle for cancer patients, though they can be a bit demanding.
We are lucky in having here a member, "Nano Second", who is on Sutent and who has gone in considerable depth into what he has found to be helpful for him and he has had just about none of the troubles